What type of variation would you expect in traits governed by a single gene with only two distinct alleles?

In traits governed by a single gene with only two distinct alleles, you would expect to see discontinuous variation. This type of variation is characterized by distinct categories or phenotypes, rather than a smooth range of traits.

With only two alleles, individuals can only express one of two possible phenotypes, such as dominant or recessive traits. For example, in a simple trait like flower color, if one allele codes for red flowers and the other for white, the plants will either have red or white flowers, with no intermediate colors. This stark division exemplifies how discontinuous variation operates; individuals belong to discrete groups rather than displaying a spectrum of traits.

In contrast, continuous variation involves traits that can be expressed on a gradient, such as height or skin color, where multiple genes contribute to a range of phenotypes. Quantitative and polygenic variations also relate to multiple genes influencing a single trait, leading to a broad spectrum, which further supports the idea that single-gene traits manifest as distinct categories rather than varying continuously.